Formation of N2 from Pyrrolic and Pyridinic Nitrogen during Pyrolysis of Nitrogen-Containing Model Coals

Abstract

Two model coals, one containing pyrrolic nitrogen and another containing pyridinic nitrogen, have been used to study N2 formation from different nitrogen structures during coal pyrolysis. The formation of N2 during pyrolysis of the model coals with and without a catalyst has been investigated in a fixed-bed reactor at 2.5−10 °C/min up to 1000 °C. The pyrolysis results show that calcium and iron catalyze both pyrrolic and pyridinic nitrogen in model coals to N2. Calcium-catalyzed N2 formation occurs at temperatures higher than 800 °C; however, the iron catalyzes N2 formation at temperatures below 800 °C. The remarkable formation of N2 results in low residual nitrogen in char. It is suggested that the calcium and iron catalysts catalyze N2 formation mainly through solid-phase reactions of pyrrolic and pyridinic nitrogen forms in char.